diff --git a/.changeset/wise-cars-rhyme.md b/.changeset/wise-cars-rhyme.md
new file mode 100644
index 0000000000..befe029d63
--- /dev/null
+++ b/.changeset/wise-cars-rhyme.md
@@ -0,0 +1,5 @@
+---
+'nextra-theme-docs': patch
+---
+
+handle empty `item.route` in `<FolderImpl` in `<Sidebar>` for `item.type: 'menu'`
diff --git a/packages/nextra-theme-docs/src/components/sidebar.tsx b/packages/nextra-theme-docs/src/components/sidebar.tsx
index f16cd9e4f6..389f85991d 100644
--- a/packages/nextra-theme-docs/src/components/sidebar.tsx
+++ b/packages/nextra-theme-docs/src/components/sidebar.tsx
@@ -72,8 +72,10 @@ type FolderProps = {
 function FolderImpl({ item, anchors, onFocus }: FolderProps): ReactElement {
   const routeOriginal = useFSRoute()
   const [route] = routeOriginal.split('#')
-  const active = [route, route + '/'].includes(item.route + '/')
-  const activeRouteInside = active || route.startsWith(item.route + '/')
+  const hasRoute = !!item.route // for item.type === 'menu' will be ''
+  const active = hasRoute && [route, route + '/'].includes(item.route + '/')
+  const activeRouteInside =
+    active || (hasRoute && route.startsWith(item.route + '/'))
 
   const focusedRoute = useContext(FocusedItemContext)
   const focusedRouteInside = focusedRoute.startsWith(item.route + '/')
@@ -130,7 +132,6 @@ function FolderImpl({ item, anchors, onFocus }: FolderProps): ReactElement {
     item.children = Object.entries(menu.items || {}).map(([key, item]) => {
       const route = routes[key] || {
         name: key,
-        ...('locale' in menu && { locale: menu.locale }),
         route: menu.route + '/' + key
       }
       return {